In the related art, there is a capacitive touch panel which detects a position of an object such as a finger of an operator or a pen on the basis of a variation in a capacitance. A touch input device using this capacitive touch panel is generally used in combination with a display device such as a liquid crystal display.
The touch input device generally includes a touch panel provided with a plurality of driving electrodes and a plurality of detection electrodes forming capacitances with the respective driving electrodes, a driving circuit connected to the plurality of driving electrodes, and a detection circuit connected to the detection electrodes. The plurality of driving electrodes are sequentially driven by the driving circuit, and a sampling capacitor in the detection circuit is charged by electric charges which are induced in the detection electrodes. A position of an object is detected based on a comparison result between a voltage held in the sampling capacitor and a predetermined threshold voltage.
In the above-described touch input device, if the area (width) of the driving electrode is small, the number of driving electrodes which can be disposed on the touch panel increases, and thus a position of an object is finely detected, but, on the other hand, a variation in a potential output from the detection electrode is reduced. In contrast, if the area (width) of the driving electrode is large, a variation in a potential output from the detection electrode increases, but, on the other hand, the number of driving electrodes which can be disposed on the touch panel is reduced, and thus a position of an object cannot be finely detected. In other words, there is a trade-off in relation between an S/N ratio in detecting a potential variation of the detection electrode and detection accuracy (which refers to a resolution of position detection in a direction in which the driving electrodes are arranged). In addition, hereinafter, there are cases where a description is made assuming that a dimension of the area of the driving electrode is the same as a dimension of the width of the driving electrode.
In relation to the present invention, PTL 1 discloses a touch input device in which m driving electrodes with a reduced width are driven together, and (m−1) driving electrodes are made to overlap each other among the m driving electrodes which are driven in continuous selection periods. Accordingly, when a position of an object such as a finger with the relatively large area is detected, it is possible to improve detection accuracy and to suppress an S/N ratio from being reduced.